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Sem 2 Infectious Diseases > Week 4 - Viral anthropathies > Flashcards

Week 4 - Viral anthropathies Flashcards

1
Q

WHat does arthralgia mean?

A

Joint pain

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2
Q

What is arthritis?

A

Joint inflammation

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3
Q

What does oligoarthritis mean?

A

A few joints are affected - = or

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4
Q

WHat would ‘rheumatoid like’ refer to?

A

Distal, symmetrical polyarthropathy

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5
Q

What is reactive arthritis?

A

May see conjunctivitis, uveitis and arthritis

– Follows infections

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6
Q

WHat are some major causes of inflammatory polyarthritis?

A
  • Infectious arthritis
  • Reactive arthritis
  • Seronegative spondyloarthritis
  • Rheumatoid arthitis
  • Inflammatory osteoarthritis
  • Crystal-induced arthritis
  • Systemic rheumatoid arthritis
  • Other systemic illnesses (i.e. sarcoidosis)
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7
Q

Which families of viruses cause arthritis?

A

Arboviruses
Parvoviruses
Rubella
Others

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8
Q

What type of viruses are arboviruses?

A

RNA viruses surrounded by a lipid envelope, transmitted by arthropod vectors

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9
Q

What does viscerotropic mean?

A

Causes fever/rash/arthritis

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10
Q

What types of arboviruses are viscerotropic?

A
  • Togaviridae - Chikungunya, RRV
  • Flaviviridae - Dengue
  • Bunyaviridae - Sandfly fever
  • Reoviridae - colorado tick fever
  • Zika virus (flavivirus)
  • Barmah forest (alpha)
  • Sindbis (alpha)
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11
Q

How can you reliably exclude dengue fever from travellers?

A

If it’s been more than 14 day since exposure - incubation period is 3-14 days mean 4-7

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12
Q

How many serotypes of dengue are there?

A

4, with minimal cross over

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13
Q

What does it cause and from which region are you most likely to get it?

A

Systemic, febrile illness,

Travellers from SE asia

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14
Q

What does it cause and from which region are you most likely to get it?

A

Systemic, febrile illness,

Travellers from SE asia

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15
Q

Describe classical dengue fever

A

Break-bone fever: fever, headache, retro-orbital pain and marked muscle and joint pain

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16
Q

In what % of dengue fevers do you have a rash? Describe the rash

A

slightly more than 50%

Macular/maculopapular +/- pruritis

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17
Q

What are long term symptoms of dengue fever infection?

A

Marked fatigue following infection - days to weeks

More in adults than children

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18
Q

In what % of classical dengue do haemorrhagic manifestations occur?

A

70% - can be lifethreatening - GI occur in 4%

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19
Q

What characterises severe dengue?

A

Severe plasma leakage
Severe haemorrhage
Severe organ impairment

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20
Q

What are the warning signs that separate non-severe dengue with warning signs and non-severe dengue without warning signs?

A
  • Abdominal pain/tenderness
  • Persistent vomiting
  • Mucosal bleeding
  • Lethargy/restlessness
  • Liver enlargement
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21
Q

Who gets severe dengue?

A
  • Secondary infection with another subtype

- Children

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22
Q

How do you diagnose dengue?

A

Confirm with seroconversion, four-fold rise in specific IgG tire or detection of virus using NAT or viral culture - NAT only good in first few days
-Special dengue test called NS1 antigen - accurate and specific

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23
Q

What will bloods show with dengue

A

Leukopenia, thrombocytopenia, raised AST

24
Q

What are serology methods of detection?

A
  • EIAs - enzyme immunoassay
  • IFA - immunofluorescence assay
  • HAI - haemagglutination inhibition
    IHA - indirect haemagglutination
25
Q

What are the main differences between dengue and Chikungunya?

A
  • More joint pain and joint swelling with chik (65% vs 4%)
  • More abdominal pain and leukopenia with dengue
  • Bleeding manifestations and severe thrombocytopenia are relatively specific for dengue
26
Q

Zika virus details?

A

ssRNA
Enveloped
Mosquito as vector - aedes aegypti
Flaviviridae family - same as dengue, yellow fever and japanese encephalitis

27
Q

What is happening with Zika in Aus?

A

Total cases are rising. Most common in Qld and Vic

28
Q

How an Zika be transmitted to humans?

A
  • Bite of infected mosquito
  • Maternal-foetal transmission
  • Sex
  • Blood transfusion
  • Organ transplant
  • Lab exposure
29
Q

What are clinical features of Zika virus?

A

75% are asympomatic

In adults and children:

  • Mild fever
  • Full body maculopapular pruritic rash
  • Arthralgia in small joints of hands and feet
  • Conjunctivitis
  • Less common - headaches/GI symptoms
  • Pregnancy doesn’t mean more severe disease
  • Infection = immunity
30
Q

What are the two main complications of Zika?

A

Guillain-Barre syndrome

Congenital infection

31
Q

What happens in Guillain-Barre syndrome?

A

Ascending, progressive muscle weakness

  • Usually triggered by prior resp or GIT infection
  • Acute motor axonal neuropathy
  • Direct nerve toxicity from virus
32
Q

What are consequences of congenital zika?

A
  • Microcephaly and other CNS abnormalities
  • OCular abnormalities
  • Foetal loss
33
Q

How do you diagnose ZIka?

A

Confirm with seroconversion/4-fold increase in IgG between acute and convalescent, NAT/viral culture
IgM is suggestive
PCR can also be positive in urine for the 1st 2weeks, blood for the first week

34
Q

What are the two australian arboviruses?

A

RRV - most common vector borne disease in Australia, outbreaks after rain and macropods are principle animal hosts
Barmah Forest virus - Endemic in northern Australia, multiple mosquito vectors, peak transmission in summer/autumn

35
Q

What are clinical features of RRV?

A
  • Incubation 3-9 days, up to 21
  • Acute fever, rash and arthritis
  • Chronic arthritis
  • Arthralgia/arthritis is ue to immune, often in extremities and symmetrical (like gout)
  • ESR mildly up
  • Diagnose with serology
  • Treatment is supportive
36
Q

What are the clinical differences between RRV and Barmah Forest?

A

Barmah causes a more mild disease than RRv
_ more common rash in Barmah
- More severe joints in RRV

37
Q

How do you diagnose RRV/Barmah?

A

Serology
NAT/viral culture
IgM is only suggestive

38
Q

Why would you not want to use IgM to diagnose viruses?

A
  • False positive IgM
  • Cross reactive IgM i.e. within families is quite extensive
  • Persistent IgM - can last months
  • Lack of IgM in secondary infections
  • Late IgM in seriously ill patients
39
Q

What are the differences in rubella manifestations between adult and children?

A

Adults are more symptomatic, have a longer arthralgia and arthritis in women - similar to RA
Children get childhood exanthema - face to extremities, sparing palms and soles, with severe and severe lymphadenopathy

40
Q

What is Rubella incubation?

A

14-21 days

41
Q

How is Rueblla transmitted?

A

Resp. droplets/vertical

42
Q

How do you diagnose rubella?

A

IgG sero/4-fold rise, NAT on tissues, resp samples, saliva and urine

43
Q

Where does rubella like to grow?

A

Synovial tissues

44
Q

When do you want to do serology testing for Ruvella?

A

Usually on the day of rash, apart from IgG in ELISA in which case it’s 3 days after rash

45
Q

When is serology most accurate for rubella?

A

BEFORE rash shows up

46
Q

What does parvovirus B19 do?

A

Infects erythroid precursor cells –> death and inhibits erythropoises

47
Q

How is parvo transmitted and what’s it’s incubation?

A

Transmitted by resp. droplets,

Incubation 12-18 days

48
Q

When is parvo infectious?

A

Before onset of rash/joint symptons. Not contagious once rash shows up

49
Q

WHat are symptoms of parvo?

A
  • Slapped cheeks
    25% asymptomatic
    50% non-specific flu symptoms
    25% - slapped cheeks in children while adult women get arthralgia that’s acute and symmetrical, usually in small joints. Also get a rash
50
Q

Are children or adults more likely to have joint symptoms with rubella?

A

Adults - 60% vs 8%

51
Q

What are complications of rubella?

A

Foetal infection –> foetal hydrops
Blood disorders –> transient aplastic crisis
In immunocompromised - chronic anaemia

52
Q

How do you diagnose rubella?

A

IgG seroconversion/4-fold, PCR of blood is good bc there’s lots of virus even when IgM is around

53
Q

What are some other viruses with joint symtoms

A
  • Hep A has arthralgia and rash in 10-15%
  • Hep B - hands, knees and large joints
  • Hep C - RA like, can be oligoarthritis
  • HIV - reactive arthritis
  • EBV
    Adenovirus
    -HSV
    -Ebola
54
Q

What do you need to be aware of with serology testing?

A

False positives/negatives

Problems with IgM - can takes weeks to develop, may persist for months and may be reinfection rather than primary

55
Q

What are methods of direct virus detection and when are they useful?

A

Culture and PCR - need to do them within 5 days

Sem 2 Infectious Diseases (3 decks)

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